NCERT Mathematics, Class 11, textbook pages 24–42

How to help your child with Class 11 Maths Chapter 2, Relations and Functions, at home

Cartesian products, relations and functions, explained for parents: a 45-minute study session, a quick challenge, a 5-day plan and the mistakes to watch for.

1a2b3ceach input → one output: a function

NCERT Class 11 Maths Chapter 2 Relations and Functions: what it teaches

Your teen forms ordered pairs and Cartesian products, defines relations with domain and range, and learns what makes a relation a function, with graphs of common functions like linear, modulus and greatest integer.

Why it matters later. Functions are central to calculus (Chapter 12) and Class 12.

See it: this chapter in pictures

A = {1, 2}, B = {x, y, z}A × B has 6 pairs(1, x), (1, y) …
Every pairing of elements.
{(1, 2), (1, 3)}1 has two outputsnot a function
One input, one output.
f(x) = |x|
The modulus function makes a V.

You need

  • graph paper
  • a list of students and their birth months

Tonight’s 45 minutes

  1. Write A × B for A = {1, 2}, B = {x, y, z} (6 pairs).
  2. Map students to birth months. Is it a function? (Yes: each student has one month.)
  3. Map months to students. Function? (No: a month may have many students.)
  4. Graph f(x) = |x| and f(x) = [x].

Words to use

  • ordered pair
  • Cartesian product
  • relation
  • function
  • domain
  • range
  • codomain

Watch for

  • Calling any relation a function. Each input must have exactly one output.
  • Mixing range and codomain. Range is the set of actual outputs.

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouIs ‘student → birth month’ a function?

Your childYes, each student has one month.

A game for this week: Function or not?

  1. Write relations as arrow diagrams.
  2. Players decide: function or not.
  3. Explain why.
  4. Point per correct answer.

A 5-day plan, 45 minutes a day

  1. Day 1Explain-back.
  2. Day 2Worked examples.
  3. Day 3Practice set.
  4. Day 4Real-life problem.
  5. Day 5Mixed quiz.

Everyday moments to practise

  • Price as a function of quantity.
  • Temperature over time.
  • Tax slabs.
  • Mobile data charges.

Quick check

Ask these at the end of the week. Tap to see the answer.

n(A × B) if n(A) = 2, n(B) = 3?

6.

Is {(1,2), (1,3)} a function?

No.

Range of f(x) = x², x real?

[0, ∞).

Ready for the next chapter when your child…

  • Forms Cartesian products.
  • Identifies functions.
  • Finds domain and range; sketches graphs.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Mathematics (Class 11). See the full Class 11 parent guide for every chapter.

Questions parents ask

What is a function?

A relation where each input has exactly one output.

How do I find the range?

Find all possible outputs, often from the graph.

What is the greatest integer function?

[x] is the greatest integer less than or equal to x.